The present invention relates to a placer mechanism for placing labels on a product and, more particularly, to a placer mechanism and method for a web of linerless labels for accurately and efficiently placing individual labels on a conveyed product.
There are a number of commercial placer mechanisms for labeling products of a wide dimensional variability and size, using conventional liner-type label product either from sheeted singles or web fed rolls. These placing machines are well developed, and it is generally a simple set up to synchronize the location of the label to the product by xe2x80x9ctackingxe2x80x9d the label onto the product, then continuing to feed while the label attaches to the product and the liner is simultaneously removed and discarded.
With linerless labels, however, the label must be cut or detached from the web of label stock and handled with the full adhesive surface of each label exposed and ready to xe2x80x9cgrabxe2x80x9d the first thing that the adhesive side may contact. This unwanted adhesive attraction can be reduced to acceptable levels within the cutter or burster mechanism by applying a non-stick plasma coating to all surfaces contacting the adhesive and/or by using silicon elastomer rollers, etc., but the label must be held in correct placement alignment to accurately meet the product to which the label is to be attached.
Where relatively short labels, i.e., four inches or less in length, are to be processed, they may be fed to a stationary vacuum platen that can then be driven into contact with the product by air cylinder or other mechanical means. Another method is to use a vacuum cylinder to xe2x80x9cgrabxe2x80x9d the label emerging from the cutter, then rotate the cylinder, with label aboard, until the label leading edge correctly aligns with the product, and then transfer the label from the severing mechanism directly to the product.
Neither of these methods is satisfactory for a wide range of label sizes. The main deterrent to these simple transfer systems is that the basic feeder and cutter is, by good design, very compact, with very short paper paths to lessen the problems of label curl, static and internal jamming usually associated with any feeding aberration of these sticky labels. With the web path shortened to minimize these problems, on any label longer than the internal path from the separator, it then may be necessary to apply the label leading edge to the product while the tail end of the label is still within the separating module. Since the label is stopped during the separator cycle, a problem arises wherein if a product happens to come along, it will tend to grab the leading edge of a yet unsevered label.
Another problem is that a label being fed from the applicator must be safely separated from the product stream during feeding and aligning between the two deliveries, thus requiring that either the label must be brought to the product to which it is to be attached, or the product must be brought to the label, or both, before pressure is applied to the label/product union.
According to the present invention, there is provided a placer mechanism for a web of linerless labels for placing individual labels on a product. The placer mechanism includes a separator that separates the individual labels from the web; a buffer disposed downstream of the separator that receives the individual labels; and a buffer suspension assembly movably supporting the buffer such that the buffer is positionable to deliver the individual labels to the product.
The buffer preferably consists of a rotatable vacuum drum including a vacuum for generating a vacuum surface on the rotatable vacuum drum. The buffer suspension assembly may include an actuating cylinder pivotally supporting the rotatable vacuum drum.
A feeding assembly may also be provided. The feeding assembly feeds the web of linerless labels to the separator and feeds the individual labels to the buffer. The feeding assembly preferably includes a pair of web driving rolls that drive the web to the separator; a label guide that guides the individual labels toward the buffer; and a pair of individual label driving rolls that receive the individual labels from the label guide and that drive the individual labels to the buffer. To prevent slack, the individual label driving rolls may be configured to rotate faster than the pair of web driving rolls, and the rotatable vacuum drum may be configured to rotate faster than the individual label driving rolls.
A first sensor may be provided for the feeding assembly for sensing a cutting position of the web of linerless labels to activate the separator, and a second sensor may be provided for sensing a location of the product to activate the buffer suspension assembly to position the buffer for product label application.
The label guide preferably includes a plurality of wires attached to two support rods, wherein the wires are skewed from a centerline position of a web path. The wires may each comprise a plasma coated surface.
In accordance with another aspect of the invention, there is provided a method of placing individual labels on a product with a placer mechanism from a web of linerless labels. The method includes separating the individual labels from the web; transferring the individual labels to a buffer; and positioning the buffer to deliver the individual labels to the product.
The method may further include generating a vacuum surface on the rotatable vacuum drum, and/or, prior to the separating step, feeding the web of linerless labels to the separator. The placer mechanism is preferably provided with a feeding assembly including a pair of web driving rolls that drive the web to a separator for the separating step, a label guide that guides the individual labels toward the buffer, and a pair of individual label driving rolls that receive the individual labels from the label guide and that drive the individual labels to the buffer, wherein the method may further include rotating the individual label driving rolls faster than the pair of web driving rolls, preferably about 5% faster. The buffer may consist of a rotatable vacuum drum, wherein the method includes rotating the rotatable vacuum drum faster than the individual label driving rolls, preferably about 10% faster.
During the separating step, the method may include pivoting the label guide to maintain a clear path for the individual labels. In addition, the method may include sensing a cutting position of the web of linerless labels to activate the separating step, and/or sensing a location of the product to activate the positioning step.
Accordingly, it is a primary object of the present invention to provide a novel and improved placer mechanism and method for a web of linerless labels for placing individual labels on a product that can accommodate linerless labels of various sizes and in a manner that enables accurate and efficient placement of the labels.